Hi, I'm a newbe and have heard how silver coins and others may be tampered with. (cleaned ect) How is it possible to detect? Thanks for the help and sorry I bet someone has asked this before. I do have a microscope and have looked at coins, just don't know what to look for. Tim
It usually depends on the coin. Silver is hard to detect correct dipping. If a silver coin is overdipped, it will have a rather dull and dead appearance. If a coin has wear on it, but no traces of toning or dirt on it then it is probably cleaned. Copper and bronze will have a pinkish color to it if it has been cleaned. Copper nickel Indian Cents will show more copper at the surface of the coin than an uncleaned specimen. Once you get used to looking at coins from various years, you will know what an uncleaned one will look like compared to a cleaned one. A circulated Indian Head cent will have a dark, almost chocolate brown color. One that is pinkish or bright red will be a dead giveaway. Silver is harder, but you can still tell if it has been cleaned and allowed to retone. The most important thing to check is for evidence of mint lustre in an uncirculated coin. You can't fake mint lustre, once it's gone it's gone. It is the metal flow lines caused by the forces of the die as well as the surfaces of the dies themselves which is transferred to the coin during the striking process. A proof coin will have a mirrorlike appearance that cannot be repaired during cleaning. A mint state coin will have a series of concentric rings that have a cartwheel like effect on the coin. Some dealers have tried to fake this by running a brass brush over it. This is called whizzing, you can easily tell under a microscope or loupe because there will be a series of scratches. Cleaning will also cause hairline scratches and is easily detectable. Some proof coins have a frosty effect on the high points which is caused by the mint sandblasting the die. The mirrorlike surfaces are from the die being polished. Neither one can be faked. Just because a coin is missing detail, doesn't mean that it's not a mint state coin. It may not be fully struck or struck on an old die. Toning may hide the coin's defects. It can cover up previous cleanings and mishandlings. Sometimes coins are artficially toned with chemical agents or with heat. Look at other coins in that set to see if the coin looks funny compared to them. Artificially toned coins will have unnatural colors and the toning will seem to be resting or floating on the surface of a coin. There are many things to look for and consider when you are looking at coins. Advice cannot replace experience. Even some dealers are fooled from time to time when it comes to dipping and artificial toning. Grading companies have known to make these mistakes from time to time as well.
Here are some pics of a Morgan I have that was overdipped. Notice the dull appearance. The cartwheel effect is almost completely gone.
Note the Morgan Dollar has a goldish, brassy color to it. This is caused by the dip removing the silver and leaving the copper. Coin silver is 90% silver, 10% copper.
You can also tell if an ancient silver coin is fake by doing a ring test. If itmakes a silver ringing noise, it's fake. But if it makes more of a thud, then it's authentic. This is caused by the silver corroding inside the coin, it usually leaches out of it was buried and can leave ancients brittle and fragile. Old silver dollars will probably have less of a ring to them then newly minted ones.
Go Thanks for the replys. It is very cool having people with experience to help out us novices. I have picked up on useful information just lurking in the background. Thanks Tim
Pyro I would have to respectfully disagree with the last two posts you made. Genuine silver coins do ring - fake ones don't. And the silver and copper is an alloy, it's not layered. You can't remove one from the surface and leave the other. I would agree though that the coin has a dip residue on it. Tim, do a search for the word cleaning. You'll find a great many discussions on the subject.
It is possible to fake the ring of silver without having any silver content in the coin. Genuine ancient coins are usually worth far more than their metal content and many good counterfeits are made with real silver. Genuine ancient silver coins will crystalize over time and the silver will leach out. This changes the internal structure of the coin and will effect how the coin rings. With the Morgan Dollar specimen, the surface has corroded and the silver from the surface has been removed more than the copper atoms. Coin silver is an alloy which means that the metals are evenly distributed throughout the entire coin. The silver on the surface has been removed without disturbing the copper atoms which is why it has taken on it's current appearance.
In the ancient coins, it's not the silver that leeches out - it's the copper and other impurities. Yes, it can be that to some this will happen - but not to all of them. And even then it only happens to those that are buried and in contact with the soil. If the coins were stored in pottery, as many of them were when they were buried - it doesn't happen at all. And yes I will agree that other metals will ring like silver, even copper and bronze ring as does gold. But fake "silver" coins do not - unless they are made of silver. But typical fake silver coins are plated or they have a very debased silver content - and those don't ring.
